This game contains more than 800 unique items, all of them came from pokemon official games.

In this game to earn exp, you have this methods below:

Battling wild pokemon,Battling trainers,Using Exp Share,Using Luckyegg,Hatching a pokemon with this sign: "The Scholar", this sign always gives to that pokemon more 20% exp and it can stack with items like exp share.

I'll give you a hint: You can get exp share by quests and through some special npc after hoenn region. And to get lucky egg, you can use thief on wild pokemon, for example chansey or special npc after hoenn region.

You have early exp help, in kanto you have a quest to earn exp share and you can thief wild chansey hold item lucky egg.

And the next and best option is the Birthsign system after hatching a pokemon in september to earn "the Scholar" birthsign to increase + 20% exp in battles and this effect is permanent.

Example: Killing a Rattata gives 50 exp +20% extra from birthsign + exp share = lots of exp according to wild lvs.If you kill Rattata lv5 and you have a pokemon lv50, you will got minimun exp for the diferences of lvs.

I will give you a hint, but i consider it a cheat code: If you change your PC clock and days and mounths, it will change in the game's too.

Also in another regions you can earn more exp share items by doing quests.